用python+selenium获取北上广深成五地PM2.5数据信息并按空气质量排序

从http://www.pm25.com/shenzhen.html抓取北京，深圳，上海，广州，成都的pm2.5指数，并按照空气质量从优到差排序，保存在txt文档里

代码如下：

 #coding=utf-8
 from selenium import webdriver
 from time import sleep

 class PM:

     def __init__(self):
         self.dr = webdriver.Chrome()
         self.pm25_info = self.get_pm25_info()

     def get_pm25_info(self):
         city_list = ['beijing','shenzhen','shanghai','guangzhou','chengdu']
         pm_info_list = []
         i = 0
         while i < len(city_list):
             self.dr.get('http://www.pm25.com/'+city_list[i]+'.html')
             sleep(3)
             city_name = self.dr.find_element_by_css_selector('.bi_loaction_city').text #定位城市名字
             pm_exp = self.dr.find_element_by_css_selector('.pm25_span').text #定位PM2.5指数
             air_num = self.dr.find_element_by_css_selector('.bi_aqiarea_num').text #定位AQI指数
             air_quality = self.dr.find_element_by_css_selector('.bi_aqiarea_right span').text #定位空气质量描述
             pm_info_list.append((city_name, pm_exp, air_num, air_quality))
             i += 1
         pm_info_list.sort(key=lambda x:float(x[2])) #按AQI指数排序(AQI指数决定了空气质量的优良)
         return pm_info_list

     def get_pm_info_file(self):
         self.file_title = '北上广深成五地PM2.5数据信息'
         self.file = open(self.file_title + '.txt', 'wb')
         self.floor = 1
         for item in self.pm25_info:
             separate_line = '**********' + 'TOP' + str(self.floor) + '**********\n'
             self.file.write(separate_line.encode('utf-8'))
             self.file.write(('城市：' + item[0] + '\n'
                              'PM2.5指数：' + item[1] + ' '+ '微克/立方米' + '\n'
                              'AQI指数：' + item[2] + '\n'
                              '空气质量：' + item[3]+ '\n').encode('utf-8'))
             self.floor += 1
         self.file.close()

     def quit(self):
         self.dr.quit()

 if __name__ == '__main__':
     pm_info = PM()
     pm_info.get_pm_info_file()
     pm_info.quit()

网页如下：

生成txt如下：